Eukaryotic gene control is the topic common to three studies presently performed in my laboratory. The first of these concerns early adenovirus gene regulation. In a microinjection assay, we examine complex adenovirus gene interactions resulting in the expression of the defective adeno-associated virus. The second study deals with rearrangements in the genome of adeno-SV40-hybrid viruses. In collaboration with Dr. A. Lewis, Jr., we investigate the possibility that the observed genomic changes are directed by constraints in RNA processing. The third study involves gene transfer into the early stage mouse embryo. The goal of this line of experiment is to study the expression and control of a defined gene during animal development. DNA is injected into mouse zygotes, which are reimplanted into foster mothers. Integration and expression of the transferred DNA is monitored after birth of live offspring. Gene constructs presently tested contain signal genes whose products can easily be scored and which are placed under the control of a variety of promoters.